Apparatus for cementing well liners



Jan. 23, 1968 r c. c. BROWN 3,364,996

APPARATUS FOR CEMENTING WELL LINERS Filed Feb. 4, 1966 5 Sheet sShee t l /LEPO L. B/POW/V I N VENTOR.

AT T Ole/V51 Jan. 23, 1968 c. c. BROWN APPARATUS FOR CEMENTING WELL LINERS 5 Sheets-Sheet 2 Filed Feb. 4, 1966 ATTORNEY CL C. BROWN APPARATUS FOR CEMENTING WELL LINERS Jan. 23, 1968 3 Sheets-Sheet 3 Filed Feb. 4, 1966 United States Patent Ofiice 3,364,996 Patented Jan. 23, 1968 3.364396 APPARATUS FOR CEMENTENG WELL LINERS Cicero C. Brown, Brown Oil Tools, Inc., R0. Box 19235, Houston, Tex. 77024 Filed Feb. 4, 1966, Ser. No. 525,065 11 Claims. (Cl. 166-120) This invention relates to improvements in apparatus for use in cementing well liners.

Conventionally, liner cementing is conducted by introducing a body of cement through an operating string and displacing the cement into the annular space between the liner and the well bore, generally to a point inside a surrounding casing to which the upper end of the liner is usually anchored. A single wiper plug is ordinarily introduced into the liner string immediately back of the body of the cement in order to separate the latter from the displacing fluid and to wipe the cement from the liner surface as the body of the cement is pushed out of the liner.

In my US. Patent No. 2,621,742, I have disclosed an improved apparatus and procedure by which the single plug is of two-part construction comprising a tubular wiper element releasably attached to the running string, and a plugging element adapted to be pumped through the running string behind the cement and into the bore of the wiper element, thereby sealing off the latter and permitting application of fluid pressure to the composite plug to release the plug from the running string and allow it to be pushed ahead of the displacing fluid through the liner to anchoring engagement with a landing collar located adjacent the lower end of the liner.

As the well bore and the liner will ordinarily be filled with well fluid or mud prior to introduction of the cement, it is also desirable to introduce a wiper plug in front of the cement body to separate it from the body of well fluid preceding it, to thereby avoid contamination of the cement. However with such a two-plug system, it is necessary when the first plug lands, that some type of opening be provided to allow the cement to discharge from the lower end of the liner into the annular space surrounding the liner. The use of such a two-plug system for liner cementing has not heretofore been successfully accomplished and the present invention has for one of its important objects the provision of a multiple plug system especially applicable for liner cementing.

Conventionally, the liner string will also include an expansible packer which will usually be set to seal off the annulus between the liner and the surrounding well casing as soon as the cement is in place. However, in conventional apparatus the packer will be permanently attached to the liner string and will be left in the well. Also, when it is necessary, as is often the case, to squeeze the cement below into the surrounding formations, it becomes necessary to shoot holes in the liner below such a permanentlyinstalled packer in order to apply the pressurizing medium. This is both a difiicult operation and one which may result in permanent damage to the liner string and the seal formed by the cement.

It is, therefore, another important object of the present invention to provide a liner cementing apparatus which includes a packer which is releasably connected to the liner string and which may initially be expanded while the cement is taking its initial set to relieve the cement from the hydrostatic loads of the overlying fluids, and which may then be retracted if it is found necessary to squeeze the cement by pressurizing through the well annulus from above the packer. Aiso, the apparatus includes a releasable connection which enables the packer to be withdrawn from the well when cementing operations have been completed. In addition, the packer assembly includes valve means operable upon expansion or setting of the packer to open circulation passage between the well annulus and the operating string above the packer to permit washing out of any excess cement above the packer.

The apparatus in accordance with this invention, may also include a liner hanger of any conventional design and, desirably, a fluid pressure-operated hanger which may be actuated by the fluid pressures employed in the cementing operation.

The apparatus may also include as a part of the liner string, a differential pressure fill-up shoe which enables controlled filling of the liner with well fluids as it is lowered into the well in accordance with the differential in pressure between the fluid columns inside and outside the liner, and which also includes an actuating sleeve operable, upon entrance therein of the first of the plugging units, to provide by-pass passages through the shoe to enable the cement to be discharged into the well annulus while at the same time, actuating a back-pressure valve in the shoe to prevent back-flow of fluids into the liner when the cementing operation has been completed.

It is, therefore, a principal object of this invention to provide a liner cementing apparatus having exceptional flexibility enabling meeting any of a wide variety of conditions which may be encountered in the well bore and in the cementing operations.

The foregoing and various other objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate one useful embodiment in accordance with this invention.

In the drawings:

FIGS. 1a and 1b, together, comprise a longitudinal, partly sectional view of a liner cementing apparatus in accordance with one embodiment of this invention;

FIGS. 2, 3 and 4 are partly sectional, generally diagrammatic views illustrating the positions of the parts of the apparatus at several successive stages in a liner cementing operation;

FIG. 5 is a view generally similar to FIGS. 2, 3, and 4, showing the operating string and packer being Withdrawn from the liner string after completion of the cementing operations; and

FIGS. 6, 7 and 8 are crosssectional views taken, respectively, along lines 6-6, 7-7 and 88 of FIGS. 1a

,, and 1b.

Referring first to FIGS. la and lb, the apparatus assemblage in accordance with this invention is shown inserted into a well bore W, at least the upper portion of which is lined with a metal casing C extending to the surface and having thereon a conventional casing head A to which are connected valved conduits V.

The cementing apparatus comprises a liner string, designated generally by the letter L, and an operating string, designated generally by the letter O.

Liner string L includes a string of liner pipe 10 made up of a plurality of pipe sections suflicient to provide a liner of the desired length; a fill-up and cementing shoe, designated generally by the letter S, connected to the lower end of the liner by means of a coupling 12; a liner hanger, designated generally by the letter H, secured to the upper end of the string of liner pipe; an extension sleeve 13 connected to the upper end of the liner hanger body; and an expansible packer, designated generally by the letter P, releasably connected to the upper end of the extension sleeve.

Operating string 0 includes a plurality of pipe sections 14 forming a pipe string of sufiicient length to carry the liner string to the predetermined depth in the well bore. The operating string is suspended from a tubular dropping head, designated generally by the letter D, which is, in turn, suspended in any suitable and known manner by conventional derrick-supported drawworks elements (not 3 shown) for raising and lowering the apparatus in the well. The connection between the upper end of the operating string and dropping head D includes a tubular swivel connection 16 which will enable the operating string to be rotated with respect to the dropping head, for purposes which will appear subsequently.

The operating string also includes a tubular mandrel 16 connected to the lower end thereof by means of a threaded coupling 18 and extending through the bore of packer P. The lower end of mandrel 16 carries a tubular extension 20 which is rotatably secured to the mandrel by means of a swivel connection 22. The bores of the several elements thus incorporated in the operating string are all of substantially the same diameters so as to provide a continuous bore of substantially uniform diameter through the operating string.

Longitudinally spaced upper and lower liner plugging elements, designated generally by the numerals 24 and 26, respectively, also sometimes referred to herein as wiper sleeves, are releasably secured to a coupling collar 28 threadably connected to the lower end of mandrel extension 20.

Upper wiper sleeve 24 includes a tubular body 30 the upper end of which is releasably secured to the lower end of collar 28 by means of shear pins 32 (one shown). Body 30 has a bore 31 substantially matching in diameter that of the operating string. The lower end of body 30 is threadedly received in the bore of a bottom latch ring 34, the inner periphery of which forms an annular shoulder 36 extending into bore 31 and adapted to form a plug-engaging abutment as will appear subsequently. The exterior of latch ring 34 carries a split resilient lock ring 38 for locking engagement with an element of the liner string as will be later described. The exterior of body 30 has mounted thereabout a wiper element 40 formed of flexible resilient material to provide rearwardly facing cup-shaped lips 42 adapted to wipingly engage the interior wall of liner 10 while also functioning as seals against flow of fluid downwardly between the wiper element and the liner wall.

Lower wiper sleeve 26 includes a tubular body 44 having a bore 45 substantially smaller in diameter than bore 31 of the upper wiper sleeve. Body 44 has an elongate extension 46 which extends upwardly through the bore of shoulder 36 and bore 31 and has its upper end releasably secured by means of shear pins 48 to the lower ends of inwardly inclined resilient fingers 50 forming the lower end of a bowl-shaped ring 52 which is secured to the lower end of extension 20 inside the bore of collar 28. The lower end of body 44 is threadably received in the bore of a bottom latch ring 54, the inner periphery of which defines an annular shoulder 56 extending into bore 45 and adapted to form a plug-receiving abutment, as will appear subsequently. The exterior of latch ring 54 carries a split resilient lock ring 58 for locking engagement with an element of fill-up shoe S as will be later described. The exterior of body 44 has mounted thereabout a wiper element 60 formed of flexible resilient material to provide rearwardly extending cup-shaped lips 62 adapted to wipingly engage the interior wall of liner 10 while also functioning as seals against the flow of fluid downwardly between the wiper element and the liner wall.

The construction and operation of fill-up shoe S is generally like that illustrated and described in my US. Patent No. 3,062,296, but includes additional and novel by-pass sleeve elements as will now be described.

Fill-up shoe S comprises a tubular housing 64, the upper end of which threadably receives the lower end flange 66 of coupling 12. The lower end of housing 64 is closed by a cap 68 having one or more small openings 69 therethrough. The wall of housing 64 immediately above cap 68 is provided with a plurality of narrow radial slots 70 for passage of fluid to and from the interior of the housing. An annular seat ring 72 is slidably disposed in housing 64 above slots 70 and has an axial port 73 therethrough merging at its lower end-with a downwardly and outwardly bevelled seat 74. Seat ring 72 is provided diametrically thereof with a transverse slot 75 opening to the upper end of the seat ring and adapted to accommodate a transverse keeper rod 76 having its ends secured to housing 64 (see FIG. 8). A ball-shaped valve 78 is disposed in the interior of housing 64 below seat ring 72 and is resiliently biased toward seat 74 by means of a coil spring 80 which bears against cap 68. In the upper position of seat ring 72, shown in FIG. 1b, valve 78 is held away from closing engagement with seat 74 by keeper rod 76. When seat ring 72 is moved to its lower position, as seen in FIGS. 2, 3, and 4, valve 78 is freed from engagement by the keeper rod so that it is released to function as a conventional back-pressure check valve, that is, to closingly engage eat 74 in response to flow of fluid from the exterior of the liner string to the interior thereof to prevent such back-flow while permitting outward flow of fluid from the interior of the liner.

Longitudinal movement of seat ring 72 is controlled by means of a keeper ring 82 slidably mounted in housing 64 above the seat ring. The keeper ring is initially releasably secured in an upper position (FIG. 112) by means of a split resilient lock-ring 83 which is engaged in an upper latching groove 84 provided in the wall of housing 64. A plurality of angularly spaced coil springs 85 are disposed in compression between keeper ring 82 and seat ring 72 and serve to resiliently bias thelatter downwardly toward valve 78. The pressure of springs 85 acts to vary the opening through seat 74 in accordance with the differential in pressures between the fluid columns interiorly and exteriorly of the liner string as it is run into the well so as to control the rate at which the liner fills up with Keeper ring 82 is shiftable downwardly, by a downward force applied thereto in a manner to be described, to a lower position at which lock-ring 83 will lockingly engage a lower latching groove 86 in the wall of housing 64 (see FIGS. 2, 3, and 4) and thereby force seat ring 72 downwardly and lock it in the position at'which ball valve 78 is freed from engagement by keeper rod 76 whereby to act solely as a back-pressure check valve.

The foregoing description of the structure and operation of shoe S is substantially in accord with the disclosures of Patent No. 3,062,296. In the latter, shifting of keeper ring 82 to the lower position was eflected by inserting a ball or other plugging device between the body of cement and the displacing fluid, so that when the cement had been fully displaced the pressure on the plugging device, acting through the keeper ring, would shift the seat ring downwardly to free the ball valve to act as a back-pressure check valve. However, when the plugging device was so-introduced, outward flow of fluid was effectively stopped, as the plugging device closed off the port in the seat ring.

In accordance with one feature of the present invention, where two plugging units are to be employed, one to be in advance of the body of cement, it is necessary when the first plug reaches the fill-up shoe, to provide fluid passages through the shoe which will permit discharge of the cement into the well annulus. Accordingly, the fill-up shoe herein described has been modified to provide means for establishing by-pass passages around the first plug while, at the same time, establishing the backpressure characteristics of the valve in the shoe.

The modified shoe includes a sleeve 88 coaxially disposed in the bore of housing 64 above keeper ring 82.

Sleeve 88 is smaller in diameter than the bore of housing 64 to provide an annular space 89 therebetween. The

upper end of sleeve 88 is releasably secured to flange 66 of collar 12 by means of shear pins 90. The lower end of sleeve 88 is provided with a plurality of radial passages 91 adapted when sleeve 88, after release of shear pins 90, has been shifted downwardly into engagement with keeper ring 82, to communicate annular space 89 with port 73. This downward movement of sleeve 88 will open the upper end of space 89 to communication with the interior of the liner string above the upper end of the sleeve for by-passing fluid around the first plugging unit which will have plugged the bore of sleeve 88 as will appear subsequently. The interior of sleeve 88 is provided near its lower end with an annular abutment shoulder 92 and a latching groove 93 immediately therebelow for engagement by a plug element as will be described hereinafter.

An internal annular landing shoulder 94 is provided in the liner string at a suitable point above collar 12 and is adapted to function as a latching abutment for engagement with latch ring 34 of the upper wiper sleeve 24, when the latter has been released from collar 28 and shifted downwardly as will appear hereinafter.

Liner hanger H includes a tubular body 96 forming a part of the liner string and provided on the exterior thereof with a downwardly tapering conical slip expander 98. A cylinder sleeve 100 is slidably mounted about body 96 below expander 98 and carries on its upper end a plurality of angularly spaced radially movable, pipe-gripping slips 102 surrounding the lower portion of expander 98. The slips are actuatable by upward movement of sleeve 109 relative to body 96 to be urged outwardly by movement over the surface of expander 98 into anchoring engagement with the surrounding wall of casing C to anchor the liner string thereto, if such anchoring is desired.

A portion of the interior of cylinder sleeve 160 is suitably sealed off about body 96 by means of seals 103 and 104 to define a pressure chamber 105 which is in pressure fluid communication with the interior of the liner string through ports 106 provided through the wall of body 96. Cylinder sleeve 100 and slips 102 are initially held in retracted relation to expander 98 by means of shear pins 108 which releasably connect the lower end of sleeve to body 96.

It will be evident that, when desired, application of suitable fluid pressure into pressure chamber 105 through port 106 will break shear pins 168 and shift sleeve 109 upwardly along body 96 thereby moving slips 102 upwardly and outwardly over expander 98 until the slips engage the wall of easing C, thereby stopping further movement of the slips and effectively anchoring the liner string to the casing.

Packer P comprises a tubular body 110 which is slidably disposed about the exterior of mandrel 16. A flexible resilient seal member 112 is mounted about the exterior of packer body 116 and is disposed between a lower fixed abutment ring 113 and an upper abutment ring 114 which is longitudinally movable for applying axial compression to seal element 112, whereby to expand the latter into sealing engagement with the surrounding casing. Lower abutment ring 113 is fixedly secured to body 110 by being threadedly attached to the upper end of latching cage 116, which is also threadedly connected to the lower end of packer body 110. Latching cage 116 forms a portion of the connector means by which the packer is releasably secured to the liner string or, more directly, to the upper end of extension sleeve 13. The upper end of the latter is provided with a plurality of angularly spaced slots 117 which open to the upper end of the sleeve and are adapted to receive non-round lugs 118 projecting radially from the exterior of latching cage 116 whereby to permit the latter to be dis-engaged from sleeve 13 by upward movement relative thereto, while preventing relative rotation between the latching cage and sleeve 13. The lower end of latching cage 116 carries a plurality of latching dogs 124 supported from the cage for radial movement into and out of an annular latching groove 121 formed in the wall of extension sleeve 13. Dogs 120 are provided with external upwardly facing shoulders 122 which are engageable with a downwardly facing shoulder 123 defining the upper end wall of groove 121. A keeper ring 124 is mounted about the exterior of mandrel 16 and is engageable with the inner surfaces of dogs to urge the latter into latching engagement in groove 121 when the mandrel is in its initial position relative to the packer. The mandrel carries a section of external threads 125 which are arranged to engage a complementary set of threads 126 provided on the exterior of latching cage 116 whereby to hold keeper ring 124 in expansive engagement with dogs 120, as best seen in FIG. 1a. To release packer P from its connection to the liner string, it is only necessary to rotate mandrel 16 in the right-hand direction a distance sufficient to disconnect threads 125 from threads 126, thereby moving keeper ring 124- downwardly a distance suflicient to allow dogs 120 to move rearwardly out of groove 121.

Upper abutment ring 114 is secured to the lower end of a tubular setting sleeve 128 which extends upwardly about mandrel 16 and is provided near its upper end with an annular recess 129 in which is mounted a radi ally expansible and contraotible, segmented latching nut 131 which is adapted to be engaged by a set of ratchet threads 131 provided on the exterior of the mandrel at a point immediately below collar 18. Downward movement of the mandrel for a shont distance will force threads 131 through the segments of nut following release of the mandrel from latching cage 116 by rotation of the mandrel. Engagement of ratchet threads 13 1 with nut 136 will secure the packer to the mandrel for effecting retraction and removal of the latter from the well bore as will appear subsequently. Setting sleeve 128 is provided with a plurality of radial ports 132 which are in registration with ports 133 through the upper end of packer body 110, and mandrel 16 is provided near its upper end with radial ports 134 which are movable from an initial position (FIG. 1a) out of registration with ports 132 and 133, and to a lower position registering with the latter ports as a result of relative downward movement of the mandrel in effeoting release of the connection to latching cage 116 and engagement with nut 130, all as will appear subsequently. The registering position of mandrel ports 134 is shown in FIG. 4, at which position it will be seen that fluid communication is established between the interior of the mandrel and the exterior of the well bore at a point above seal 112 of the packer. The several ports 132, 133 and 134 and the related portion of mandrel 16 constitute sleeve valve means for controlling such fluid communication.

Referring now to dropping head D, it will be seen that this comprises a generally tubular body 136 having an axial bore 137 which is intersected at longitudinally spaced points by upper and lower retaining pins 138 and 139, respectively, which are threaded radially through the wall of body 136 to extend across the bore thereof. These retaining pins are adapted to initially support upper and lower plugs, designated generally by the numerals 140 and 141, respectively, which are introduced into bore 137. Lower plug 141 is dimensioned and adapted to be received in the bore of lower wiper sleeve 44 to close off the latter against fluid flow and to form therewith the first of the two plugs employed in connection with the cementing operation. Upper plug 140 is dimensioned and adapted to be received in bore 31 of upper wiper sleeve 124 to likewise close the bore thereof against fluid flow therethrough and to form therewith the second of the two plugs employed in the cementing operation. Lower plug 141 includes a solid core 142 connected at its lower end to a latch ring 143 carrying about its exterior a split resilient lock ring 144. A wiper and seal element 1 .5 is mounted about body 142 and is formed with upwardly facing cup-shaped lips 146 adapted to wipingly engage the interior of the operating string as it moves downwardly therethrough and to plug the bore of lower wiper element 26 when seated therein. To attain this position latch ring 143 is adapted to pass through the bore of shoulder 56 in sleeve 44 and to be stopped thereby against further downward movement while lock ring 144 latches beneath shoulder 56 to prevent retractive movement of the plug placing fluid into dropping head D is connected to the latter by a series of branch pipes 151, 152 and 153 fitted with control valves 154, 155 and 156, respectively. Branch pipe 151 communicates with bore 137 at a point below retainer pin 139; branch pipe 152 communicates with bore 137 at a point below retainer pin 138 and above the upper end of plug 141; and branch pipe 153 communicates with the upper end of bore 137 above plug 140. Each of the.

plugs will be released for movement downwardly through the operating string by retracting the related retaining pin at appropriate stages in the operation as will appear from the following description.

OPERATION With the parts of the apparatus arranged as illustrated in FIGS. 1a and lb, the apparatus will be run into the well through the casing head, being supported for this movement by means of the conventional derrick drawworks elements. In their initial arrangement, it will be seen that fluid in the well bore, being displaced by the entrance of the liner, will be able to flow into the interior of the liner string and the operating string through fill-up shoe 5 at a controlled rate, allowing the string to be run into the well at a high rate of speed, if desired, without damage to the surrounding earth formation or to the equipment. When the liner has attained the point in the well at which it is to be cemented, its upper end, carrying liner hanger H and packer P, will be positioned well inside the lower end of easing C. If desired, washing fluid may now be pumped through header 1'50 and branch pipe 151, valves 154 being open and valves 155 and 156 being closed, in order to circulate such washing fluid through the bore of the operating string and out of shoe S, and into the annulus whence the fluid may be returned to the sleeve and discharged through conduits V. This circulation is illustrated by the arrows in FIG. 1.

The introduction of cement B is preceded by opening valve 155 and retracting retaining pin 139, whereupon the cement will flow into the interior of the dropping head above plug 141, separating the cement from the previously introduced washing fluid or well fluid in advance thereof, and will force plug 141 downwardly through the bore of the operating string into bore 45 of the lower wiper sleeve. When plug 141 is engaged about shoulder 56 in wiper sleeve 26, the pressure of the cement will break shear pins 48 releasing lower wiper sleeve 26 which will, together with plug 141, travel downwardly through the liner string, wiping the wall thereof of well fluid or washing fluid in advance of the cement until the composite plug member is pushed into the bore of by-pass sleeve 88 in the fill-up shoe. Latch ring 54 wiil then be engaged about shoulder 92 in the latter and will seal off its bore whereby the pressure, acting on the composite plug, will break shear pins 90 releasing sleeve 88 for downward movement until its lower end engages keeper ring 82, pushing the latter downwardly and forcing seat ring 72 downwardly until lock ring 83 seats in groove 86. The conclusion of this sequence of operations is illustrated in FIG. 2. Upon attainment of this position of the parts, it will be seen that ball valve 78 will now be freed to open downwardly but to close against any reverse flow of fluid, thus becoming the back-pressure check valve required in connection with the cementing operation. With by-pass sleeve 88 plugged, as shown in FIG. 2, by the composite plug formed by lower wiper sleeve 24 and plug 141, by-pass passages 89 will have been opened around this composite plug into communication with seat port 73 so that the cement following plug 141 may now be forced through the by-pass passages, ports 73, past valve 7 8 and out slots 70 into the annular space between the liner string and the wall of well W.

As is well known, the volume of cement to be introduced will have been calculated so that when it has been fully displaced from the liner it will have attained a height in the annulus which will usually be well up inside casing C, and may even be above the level of packer P, as

seen in FIG. 3. It will be further understood that as soon as the calculated body of cement has entered the dropping head the displacing fluid following the cement will he diverted into and through branch pipe 153 by closing valve 115 and opening valve 156, whereupon the displacing fluid will enter the dropping head above upper plug 140. At or immediately preceding this point in the operation, retaining pin 138 will have been retracted, releasing upper plug 140 for movement downwardly through the operating string in a position separating the body of cement from the body of displacing fluid. Plug 140 will thus be forced through the interior of the operating string, wiping the latter clean of cement as it moves downwardly therethrough until it enters bore 31 of the upper wiper sleeve 24. The resilient construction of fingers 50, which previously secured the lower wiper sleeve, will permit the upper plug to pass through the bore thereof into the bore of wiper sleeve 24, wherein the plug will be engaged by and latched to shoulder 36, thus effectively closing the bore of upper wiper sleeve 24. The fluid pressure being exerted on plug 140 will, of course, be transmitted to the composite plug and will break shear pins 32, releasing the composite plug for downward movement until latch ring 34 passes through and engages annular landing shoulder 94 which will lock the plug to the liner and prevent retraction in response to any back-pressure which may be exerted through the liner string. This position of the parts is illustrated in FIG. 3.

When both plugs have been set, as described, placement of the cement will have been completed and a number of operations may be conducted as may be required according to the conditions encountered in the well. Since the upper plug will now be positioned below the liner hanger, ports 106 will now be exposed to the pressure of the fluid displacing the cement. It may be desirable .at this stage to anchor the liner to casing C by actuating the liner hanger, although this is not always necessary and may be dispensed with by reduction of the pressure in the operating string when the second plug has been set, which has been signaled to the surface by an increase in back pressure in the operating string. If, however, it is desired to anchor the liner string to the casing, the fluid pressure will be increased from the surface to a point sufficient to break shear pins 108 which will release cylinder sleeve and the fluid pressure entering chamber will move the sleeve upwardly, thereby moving slips 102 over the surface of expander 98 until the slips bite into the wall of casing C.

As indicated, however, it may or may not be desirable to actuate the casing hanger and, indeed, the liner may be run without a casing hanger. Moreover, other conventional forms of liner hangers may be employed for securing the liner string to the casing, if that operation is to be effected.

When the cement has first been placed, it is generally desirable to relieve the body of cement in the annulus, while it is taking its initial set, from the hydrostatic head of the overlying well fluid in the well bore in order to' 126. Rotation of the operating string may be effected by the use of tongs applied to the pipe at the surface or by any other suitable or conventional means (not shown). Release of the threaded connection will allow relative downward movement of the mandrel, which will be effected by lowering of the operating string from the surface and this downward movement will accomplish several operations. Ratchet threads 131 will move downwardly and become engaged in nut 130 thereby again securing the mandrel and the operating string to the setting sleeve of the packer. At the same time, downward movement will bring shoulder 19, formed by the lower end of coupling 18, into abutting engagement with the upper end of setting sleeve 128 and the weight of the string applied thereto will move setting sleeve 128 downwardly, compressing seal 112 and'expanding the latter into sealing engagement with the wall of casing C. Also, the same relative movements will bring mandrel ports 134 into registration with ports 133 and 132. The posit-ions of the several parts at this stage of operations is illustrated in FIG. 4. As a result of these operations, it will be seen that the well annulus has now been sealed above the main body of the cement to relieve the latter from the superposed hydrostatic heads. Passageways also will now be provided above the expanded packer through which washing fluid may be circulated in the reverse direction; that is, through conduits V into the well annulus and thence through the registering ports, as shown by the arrows in FIG. 4, into the bore of the operating string. Since the latter will have been closed off by the second plug, in place following the cementing operation, the washing fluid will necessarily be forced to flow upwardly through the bore of the operating string to the surface whence it may be discharged through any of the branch pipes leading to header 150. This reverse circulation will be employed to wash out any excess cement in the well annulus above the packer. On the other hand, if it is found necessary or desirable to squeeze the body of cement in the well annulus, then before the operating string is rotated to release the mandrel from the liner string and the packer (FIG. 3), squeezing fluid may be introduced through conduits V into the well annulus and applied to the body of cement therein to whatever extent may be desired. When this has been accomplished, the packer may be set, as previously described, to retain the pressure on the cement.

Rotation of the mandrel for purposes of setting the packer and releasing the mandrel from the latching cage will, as previously described, release dogs 120, thereby releasing the packer from its connection to the liner string. As rachet threads 131 will have been engaged with nut 130, it is now possible, once the cementing steps have been completed, to withdraw the packer together with the operating string including the lower end portion of the mandrel and its extension from the well bore (FIG. 5), thereby saving the packer and mandrel parts and clearing the well bore for such operations as it may be desired to conduct after the cement has set. It will also be seen that with the two plugs in place and sleeve 88 shifted to its lowermost position, as shown in FIGS. 2 to 5, valve 78 is free to act as a back-pressure valve to prevent any back-flow of fluid into the liner string while the cement is setting.

It will be understood that various alterations and modifications may be made in the details of the illustrative embodiment within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. Apparatus for cementing well liners, comprising (A) a liner string insertible in a well bore including:

(a) a liner,

(b) a fill-up shoe carried by the lower end of the liner and having passage means communicating the interior of the liner with the exterior thereof,

(c) a tubular packer carried on the upper end of the liner string and supporting an expansible seal element,

(d) connector means releasably securing the packer to the liner string,

(B) an operating string including:

(a) a pipe string smaller in diameter than the liner and insertible therein,

(b) a tubular mandrel carried by the pipe string and extending through said packer into the liner,

(c) means connecting said mandrel to said connector means operable by rotation of the mandrel to release the packer from the liner and to simultaneously release said mandrel for downward movement relative to the packer to apply end-wise compression to said seal element for radially expanding the same,

(d) lower and upper tubular liner plugging elements mounted in longitudinally spaced relation to the lower end of said mandrel, said lower element having a smaller internal diameter than said upper element,

(e) separate pressure-releasable means securing said elements to said mandrel,

(f) first and second plug means of relatively smaller and larger diameters adapted to be successively propelled by pressure fluid through said operating string into the bores of the corresponding plugging elements to close the same for application of the pressure of said fluid successively thereto whereby to successively release the same from said mandrel for movement by the pressure fluid downwardly through said liner,

(C) longitudinally spaced lower and upper stop members in said liner cooperable with the respective plugging elements to stop downward travel thereof and to secure the same against reverse movement in the liner, and

(D) shiftable means including said lower stop member mounted in said fill-up shoe and shiftable by engagement therewith of said lower plugging element to a position opening fluid passageways by-passing said lower plugging element and communicating the interior of said liner with said passage means.

2. Apparatus according to claim 1, wherein each of said plugging elements carries annular flexible resilient elements arranged to maintain wiping and sealing engagement with the wall of said liner.

3. Apparatus according to claim 1, wherein said shiftable means comprises:

(a) a sleeve member having a seat in the bore thereof for engagement by said lower plugging element, and

(b) pressure-releasable means initially securing said sleeve member to said fill-up shoe in passagewayclosing position.

4. Apparatus according to claim 1, wherein said fillup shoe includes:

(a) check valve means controlling said passage means,

(b) movable means initially holding said check Valve means in the passage-opening position, and operable by the shifting of said shiftable means to said position opening fluid passageways to release said check valve means for movement to the passage-closing position.

5. Apparatus according to claim 1, wherein said connector means includes:

(a) a tubular latching cage secured to said packer and extending concentrically between the mandrel and the upper end portion of the liner,

(b) latching dogs supported by said cage for radial movement into and out of latching engagement with a latching groove in the inner wall of said upper end portion,

(0) a keeper member mounted about the mandrel and engageable with said dogs to hold them in latching engagement in said groove, and

(d) complementary thread sections on said mandrel and said cage cooperating when engaged for holding said keeper member in said latching engagement with said dogs.

6. Apparatus according to claim 1, wherein said mandrel and said packer carry cooperating valve elements operable in response to said relative downward movement of the mandrel in expanding said seat element to contemporaneously open fluid circulation passages communicating the interior of the operating string with the well bore at a level above the expanded seal element.

7. Apparatus according to claim 1, wherein said liner string includes a liner hanger positioned on the liner below said packer and operable to anchorthe liner to the wall of the well bore. 7

8. Apparatus according to claim 7, wherein said liner hanger is constructed and arranged to be actuated by fluid pressure applied from the interior of said liner.

9. Apparatus according to claim 1 including cooperating latch means carried by said mandrel and said packer' operable in response to said relative downward movement of the mandrel to secure the mandrel to the packer whereby to enable withdrawal of the packer from the well bore by upward movement of the operating string.

10. Apparatus according to claim 9, wherein said latch means comprises radially expansible and contractible, internally threaded, segmented nut means mounted in the bore of said packer, and a section of threads on the mandrel complementary to those in said nut means.

11. Apparatus for cementing well liners, comprising,

(A) a liner string insertible in a well bore including:

(a) a liner,

(B) an operating pipe string including:

(a) a tubular mandrel carried by the pipe string extending into the liner,

(b) means forming a releasable connection between said mandrel and said liner operable by rotation of the mandrel to release the mandrel from the liner,

(c) upper and lower tubular liner plugging'elements mounted in longitudinally spaced relation to the lower end of said mandrel, said lower element having a smaller internal diameter than said upper element,

((1) separate pressure-releasable means securing said elements to said mandrel, v

(e) first and second plug means of relatively smaller and larger diameters adapted to be successively propelled by pressure fluid through said operating string into the bores of the corresponding plugging elements to close the same for application of the pressure of said fluid successively thereto whereby to successively release the same from said mandrel for movement by the pressure fluid downwardly through said liner,

(C) longitudinally spaced lower and upper stop members in said liner 'cooperable with the respective plugging elements to stop downward travel thereof and to secure the same against reverse movement in the liner, and I (D) means incorporated in said lower stop member operable by engagement therewith of said lower plugging element to open fluid passageways between the interior of said liner and the exterior thereof bypassing said lower plugging element.

References Cited UNITED STATES PATENTS 2,621,742 12/1952 Brown 166133 2,630,179 3/1953 Brown 166--28 3,006,415 10/1961 Burns et a1. 166208 X 3,062,296 11/1962 Brown 166225 3,223,170 12/1965 Mott 166208 3,253,655 5/1966 'Brown 166-120 3,291,220 12/1966 Mott 166-208 CHARLES E. OCONNELL, Primary Examiner. DAVID H. BROWN, Examiner, 

11. APPARATUS FOR CEMENTING WELL LINERS, COMPRISING, (A) A LINER STRING INSERTIBLE IN A WELL BORE INCLUDING: (A) A LINER, (B) AN OPERATING PIPE STRING INCLUDING: (A) A TUBULAR MANDREL CARRIED BY THE PIPE STRING EXTENDING INTO THE LINER, (B) MEANS FORMING A RELEASABLE CONNECTION BETWEEN SAID MANDREL AND SAID LINER OPERABLE BY ROTATION OF THE MANDREL TO RELEASE THE MANDREL FROM THE LINER, (C) UPPER AND LOWER TUBULAR LINER PLUGGING ELEMENTS MOUNTED IN LONGITUDINALLY SPACED RELATION TO THE LOWER END OF SAID MANDREL, SAID LOWER ELEMENT HAVING A SMALLER INTERNAL DIAMETER THAN SAID UPPER ELEMENT, (D) SEPARATE PRESSURE-RELEASABLE MEANS SECURING SAID ELEMENTS TO SAID MANDREL, (E) FIRST AND SECOND PLUG MEANS OF RELATIVELY SMALLER AND LARGER DIAMETERS ADAPTED TO BE SUCCESSIVELY PROPELLED BY PRESSURE FLUID THROUGH SAID OPERATING STRING INTO THE BORES OF THE CORRESPONDING PLUGGING ELEMENTS TO CLOSE THE SAME FOR APPLICATION OF THE PRESSURE OF SAID FLUID SUCCESSIVELY THERETO WHEREBY TO SUCCESSIVELY RELEASE THE SAME FROM SAID MANDREL FOR MOVEMENT BY THE PRESSURE FLUID DOWNWARDLY THROUGH SAID LINER, (C) LONGITUDINALLY SPACED LOWER AND UPPER STOP MEMBERS IN SAID LINER COOPERABLE WITH THE RESPECTIVE PLUGGING ELEMENTS TO STOP DOWNWARD TRAVEL THEREOF AND TO SECURE THE SAME AGAINST REVERSE MOVEMENT IN THE LINER, AND (D) MEANS INCORPORATED IN SAID LOWER STEP MEMBER OPERABLE BY ENGAGEMENT THEREWITH OF SAID LOWER PLUGGING ELEMENT TO OPEN FLUID PASSAGEWAYS BETWEEN THE INTERIOR OF SAID LINER AND THE EXTERIOR THEREOF BYPASSING SAID LOWER PLUGGING ELEMENT. 